Did you plant these this year? Or have they been in ground for a few years?

If your ground freezes at any point, only Gladiolus byzantinus is likely to be safe to overwinter. With Dahlias, even if it's a mild winter, the combination of cold and wet will rot the bulbs.

They were all planted this year. But I have so many, it would take forever to dig them up, and then I need to find somewhere to put them.....

you can try covering them with a deep mulch. I have planted both twice as deep before and they overwintered for several years. they are in relatively free draining soil which helps.

Good to know, Sbg!

Thanks for all the help.

I have loads and don't want to dig them all up either! I forgot a few last year and they survived, but... we did have a mild winter. Usually I dig them up, turn them upside down and let them dry out and put them in a box in the back of the barn with some paper sacks over them. They all survived, but you have to watch out for mice! This year I am going to bite the bullet and leave them in, mulch them well and hope them don't get wet and rot. Our soil is NOT well draining unfortunately Seaburngirl!